The present invention relates to a motor assembly, and more particularly to a cooling arrangement for the motor assembly, as well as a method of cooling the motor assembly.
Motor assemblies utilizing ram air flow are employed in a variety of applications, with one such application being an aircraft. The ram air flow in an aircraft may serve various purposes, such as in cooling systems for the aircraft. For example, the ram air flow may be utilized to remove heat from various aircraft lubrication and electrical systems and/or be used to condition aircraft cabin air. When the aircraft is in flight, the movement of the aircraft creates a sufficient source of ram air flow which can be used for the purposes described above. When the aircraft is on the ground or is operating at low speeds, however, a fan is typically utilized to supply air flow to the cooling systems. Such a fan is driven by an electric motor which, in turn, must be cooled by air flowing across it. The electric motor is controlled by a motor controller that is typically disposed at a location remote from the electric motor and the ram air fan, such as in a remote rack with other controllers and/or electrical components. Both the electric motor and the motor controller require cooling to maintain effective operation. Ineffective cooling of these components may lead to failure or inefficient operation. Additionally, the remote location of the motor controller and the electric motor require distinct and excessive cooling sources and flows.
Cooling of the motor controller with the fan by locating the motor controller in close proximity to the fan also introduces undesirable effects, as fans, especially ram air fans, are located such that they draw air from the harsh ambient. Harsh in this regard describes the presence of moisture, water, corrosive substances, aircraft cleaning liquid, foreign objects, etc. The motor controllers typically require forced air cooling through the motor controller. Use of air from harsh ambient can thereby result in reduced reliability and result in shortened time between failures for such co-located motor controller.